Rear Differential leak

[Travis1807]

i was under my X5M today and noticed some oil residue on the rear diff. doesn't look to be more then a slow leak but wondering what kind of seals need to be replaced to fix this as i have never worked on this before. any help would be appreciated.

[F85MTuNED]

Looks like it might be the rear axle seal.. is it coming from the side of the rear diff?

[BadCompany]

This looks pretty similar to a leak I had in my rear diff at 23,000 miles. There is an old bulletin from BMW regarding a fix for it (the dealer initially wanted to completely replace the diff). Because it was warranty work, the diff was rebuilt. It was about $650 in parts with a discounted price.

[0-60Motorsports]

Check if the servo motors are leaking. usually its the o rings on them. easy to replace:

https://www.realoem.com/bmw/enUS/sho...diagId=33_1853

[Travis1807]

Originally Posted by F85MTuNED

Looks like it might be the rear axle seal.. is it coming from the side of the rear diff?

can't really tell just a thin layer over the entire read diff

[F85MTuNED]

Originally Posted by Travis1807

can't really tell just a thin layer over the entire read diff

Crap then that could be something else.. I know when it comes to the seals it begins to leak from the sides and would gradually get worse. Do you work on it yourself or do you want a tech to take a look?

[Travis1807]

Originally Posted by F85MTuNED

Crap then that could be something else.. I know when it comes to the seals it begins to leak from the sides and would gradually get worse. Do you work on it yourself or do you want a tech to take a look?

for this i would take it to someone bc I have a feeling i would get everything apart and have a panic attack (i would be out of my depth for sure). i got under there today and took a better look and there is def more oil built up on my exhaust pipe on the driver side.

pic 1 is psg side
pic 2 is driver side (you can def. see all the oil and the marks in it from me trying to run a rag through it)


any ideas after seeing the new pics???

[Travis1807]

Originally Posted by F85MTuNED

Looks like it might be the rear axle seal.. is it coming from the side of the rear diff?

driver side but i can't tell exactly where. check out my last post for pics.

appreciate your help

[BadCompany]

You really should thoroughly clean it, drive it for 50-100 miles and check. It will really help you locate the exact place. I know it sounds like common sense... My diff and surrounding area was much worse than your's. After cleaning, it looked perfect. 100 miles later, there was a clear small spot it was very slowly leaking from. I need to find a picture where you can see just the leak.

[BadCompany]

Here are a couple where the leak is easier to pinpoint post cleaning.

[Travis1807]

Originally Posted by BadCompany

Here are a couple where the leak is easier to pinpoint post cleaning.

Do you remember what the cause of the leak was? what did you have to replace to fix?

That def. sounds like the most educated way fwd. Appreciate the help!

[BadCompany]

Originally Posted by Travis1807

Do you remember what the cause of the leak was? what did you have to replace to fix?

That def. sounds like the most educated way fwd. Appreciate the help!

No problem. Take a look at my post above for details where I posted all the parts required for the rebuild. The dealer wanted to just replace the entire diff, but the bulletin called for a rebuild with replacement of gaskets between the superimposing gear cases and the main differential housing, etc. They thought it might be the rear axle seal too, but it was actually leaking from the case itself.

[Travis1807]

Originally Posted by BadCompany

No problem. Take a look at my post above for details where I posted all the parts required for the rebuild. The dealer wanted to just replace the entire diff, but the bulletin called for a rebuild with replacement of gaskets between the superimposing gear cases and the main differential housing, etc. They thought it might be the rear axle seal too, but it was actually leaking from the case itself.

So i got some better pics and its def coming from where the driver side axel connects to the diff. the first pic is the psg side and you can see it's clear of oil and doesn't have any rust. The 2nd and 3rd pic is the driver side and it looks like the axel is rusting into the differential. there isn't much oil on the diff b/c i cleaned it off but there is still a layer caked on the exhaust right there.

i'm curious to know why its so badly rusted. seems awkward.

think ill need to replace the axel as well as the seals?